Fixed #20989 -- Removed explicit list comprehension inside dict() and tuple()

Thanks jeroen.pulles at redslider.net for the suggestion and
helper script.

23 files changed, 38 insertions, 38 deletions

diff --git a/django/contrib/auth/hashers.py b/django/contrib/auth/hashers.py
index c4dca38252..41e3deff67 100644
--- a/django/contrib/auth/hashers.py
+++ b/django/contrib/auth/hashers.py
@@ -95,7 +95,7 @@ def load_hashers(password_hashers=None):
             raise ImproperlyConfigured("hasher doesn't specify an "
                                        "algorithm name: %s" % backend)
         hashers.append(hasher)
-    HASHERS = dict([(hasher.algorithm, hasher) for hasher in hashers])
+    HASHERS = dict((hasher.algorithm, hasher) for hasher in hashers)
     PREFERRED_HASHER = hashers[0]
 
 
diff --git a/django/contrib/gis/gdal/field.py b/django/contrib/gis/gdal/field.py
index 2415f32b26..39f5fd59bf 100644
--- a/django/contrib/gis/gdal/field.py
+++ b/django/contrib/gis/gdal/field.py
@@ -191,4 +191,4 @@ OGRFieldTypes = { 0 : OFTInteger,
                  10 : OFTTime,
                  11 : OFTDateTime,
                   }
-ROGRFieldTypes = dict([(cls, num) for num, cls in OGRFieldTypes.items()])
+ROGRFieldTypes = dict((cls, num) for num, cls in OGRFieldTypes.items())
diff --git a/django/contrib/gis/gdal/geomtype.py b/django/contrib/gis/gdal/geomtype.py
index fe4b89adeb..a287033192 100644
--- a/django/contrib/gis/gdal/geomtype.py
+++ b/django/contrib/gis/gdal/geomtype.py
@@ -28,7 +28,7 @@ class OGRGeomType(object):
               7 + wkb25bit : 'GeometryCollection25D',
               }
     # Reverse type dictionary, keyed by lower-case of the name.
-    _str_types = dict([(v.lower(), k) for k, v in _types.items()])
+    _str_types = dict((v.lower(), k) for k, v in _types.items())
 
     def __init__(self, type_input):
         "Figures out the correct OGR Type based upon the input."
diff --git a/django/contrib/gis/gdal/libgdal.py b/django/contrib/gis/gdal/libgdal.py
index 91f8d618fc..af295fd619 100644
--- a/django/contrib/gis/gdal/libgdal.py
+++ b/django/contrib/gis/gdal/libgdal.py
@@ -84,7 +84,7 @@ def gdal_version_info():
     ver = gdal_version().decode()
     m = version_regex.match(ver)
     if not m: raise OGRException('Could not parse GDAL version string "%s"' % ver)
-    return dict([(key, m.group(key)) for key in ('major', 'minor', 'subminor')])
+    return dict((key, m.group(key)) for key in ('major', 'minor', 'subminor'))
 
 _verinfo = gdal_version_info()
 GDAL_MAJOR_VERSION = int(_verinfo['major'])
diff --git a/django/contrib/gis/geometry/test_data.py b/django/contrib/gis/geometry/test_data.py
index e13e8589e6..6bab165e07 100644
--- a/django/contrib/gis/geometry/test_data.py
+++ b/django/contrib/gis/geometry/test_data.py
@@ -20,13 +20,13 @@ TEST_DATA = os.path.join(os.path.dirname(upath(gis.__file__)), 'tests', 'data')
 def tuplize(seq):
     "Turn all nested sequences to tuples in given sequence."
     if isinstance(seq, (list, tuple)):
-        return tuple([tuplize(i) for i in seq])
+        return tuple(tuplize(i) for i in seq)
     return seq
 
 
 def strconvert(d):
     "Converts all keys in dictionary to str type."
-    return dict([(str(k), v) for k, v in six.iteritems(d)])
+    return dict((str(k), v) for k, v in six.iteritems(d))
 
 
 def get_ds_file(name, ext):
diff --git a/django/contrib/gis/geos/collections.py b/django/contrib/gis/geos/collections.py
index 2b62bce22c..83153f85bd 100644
--- a/django/contrib/gis/geos/collections.py
+++ b/django/contrib/gis/geos/collections.py
@@ -87,7 +87,7 @@ class GeometryCollection(GEOSGeometry):
     @property
     def tuple(self):
         "Returns a tuple of all the coordinates in this Geometry Collection"
-        return tuple([g.tuple for g in self])
+        return tuple(g.tuple for g in self)
     coords = tuple
 
 # MultiPoint, MultiLineString, and MultiPolygon class definitions.
diff --git a/django/contrib/gis/management/commands/ogrinspect.py b/django/contrib/gis/management/commands/ogrinspect.py
index 2a29fe672a..85118e3a94 100644
--- a/django/contrib/gis/management/commands/ogrinspect.py
+++ b/django/contrib/gis/management/commands/ogrinspect.py
@@ -81,7 +81,7 @@ class Command(LabelCommand):
             raise CommandError('GDAL is required to inspect geospatial data sources.')
 
         # Removing options with `None` values.
-        options = dict([(k, v) for k, v in options.items() if not v is None])
+        options = dict((k, v) for k, v in options.items() if not v is None)
 
         # Getting the OGR DataSource from the string parameter.
         try:
@@ -110,7 +110,7 @@ class Command(LabelCommand):
             mapping_dict = mapping(ds, **kwargs)
             # This extra legwork is so that the dictionary definition comes
             # out in the same order as the fields in the model definition.
-            rev_mapping = dict([(v, k) for k, v in mapping_dict.items()])
+            rev_mapping = dict((v, k) for k, v in mapping_dict.items())
             output.extend(['', '# Auto-generated `LayerMapping` dictionary for %s model' % model_name,
                            '%s_mapping = {' % model_name.lower()])
             output.extend(["    '%s' : '%s'," % (rev_mapping[ogr_fld], ogr_fld) for ogr_fld in ds[options['layer_key']].fields])
diff --git a/django/contrib/gis/measure.py b/django/contrib/gis/measure.py
index e2e6b6bca8..9f4e968732 100644
--- a/django/contrib/gis/measure.py
+++ b/django/contrib/gis/measure.py
@@ -292,7 +292,7 @@ class Distance(MeasureBase):
         'Yard (Indian)' : 'indian_yd',
         'Yard (Sears)' : 'sears_yd'
         }
-    LALIAS = dict([(k.lower(), v) for k, v in ALIAS.items()])
+    LALIAS = dict((k.lower(), v) for k, v in ALIAS.items())
 
     def __mul__(self, other):
         if isinstance(other, self.__class__):
@@ -310,9 +310,9 @@ class Distance(MeasureBase):
 class Area(MeasureBase):
     STANDARD_UNIT = AREA_PREFIX + Distance.STANDARD_UNIT
     # Getting the square units values and the alias dictionary.
-    UNITS = dict([('%s%s' % (AREA_PREFIX, k), v ** 2) for k, v in Distance.UNITS.items()])
-    ALIAS = dict([(k, '%s%s' % (AREA_PREFIX, v)) for k, v in Distance.ALIAS.items()])
-    LALIAS = dict([(k.lower(), v) for k, v in ALIAS.items()])
+    UNITS = dict(('%s%s' % (AREA_PREFIX, k), v ** 2) for k, v in Distance.UNITS.items())
+    ALIAS = dict((k, '%s%s' % (AREA_PREFIX, v)) for k, v in Distance.ALIAS.items())
+    LALIAS = dict((k.lower(), v) for k, v in ALIAS.items())
 
     def __truediv__(self, other):
         if isinstance(other, NUMERIC_TYPES):
diff --git a/django/core/management/__init__.py b/django/core/management/__init__.py
index 2ac797ecfe..708cfc259a 100644
--- a/django/core/management/__init__.py
+++ b/django/core/management/__init__.py
@@ -99,7 +99,7 @@ def get_commands():
     """
     global _commands
     if _commands is None:
-        _commands = dict([(name, 'django.core') for name in find_commands(__path__[0])])
+        _commands = dict((name, 'django.core') for name in find_commands(__path__[0]))
 
         # Find the installed apps
         from django.conf import settings
diff --git a/django/db/backends/mysql/base.py b/django/db/backends/mysql/base.py
index 15eacec679..6483b97deb 100644
--- a/django/db/backends/mysql/base.py
+++ b/django/db/backends/mysql/base.py
@@ -537,4 +537,4 @@ class DatabaseWrapper(BaseDatabaseWrapper):
         match = server_version_re.match(server_info)
         if not match:
             raise Exception('Unable to determine MySQL version from version string %r' % server_info)
-        return tuple([int(x) for x in match.groups()])
+        return tuple(int(x) for x in match.groups())
diff --git a/django/db/backends/oracle/base.py b/django/db/backends/oracle/base.py
index fe6ac0e70c..a8421991b0 100644
--- a/django/db/backends/oracle/base.py
+++ b/django/db/backends/oracle/base.py
@@ -773,7 +773,7 @@ class FormatStylePlaceholderCursor(object):
         try:
             return dict((k, OracleParam(v, self, True)) for k, v in params.items())
         except AttributeError:
-            return tuple([OracleParam(p, self, True) for p in params])
+            return tuple(OracleParam(p, self, True) for p in params)
 
     def _guess_input_sizes(self, params_list):
         # Try dict handling; if that fails, treat as sequence
diff --git a/django/db/backends/sqlite3/introspection.py b/django/db/backends/sqlite3/introspection.py
index 92777dd910..f1d433fe0f 100644
--- a/django/db/backends/sqlite3/introspection.py
+++ b/django/db/backends/sqlite3/introspection.py
@@ -139,7 +139,7 @@ class DatabaseIntrospection(BaseDatabaseIntrospection):
                 continue
 
             # This will append (column_name, referenced_table_name, referenced_column_name) to key_columns
-            key_columns.append(tuple([s.strip('"') for s in m.groups()]))
+            key_columns.append(tuple(s.strip('"') for s in m.groups()))
 
         return key_columns
 
diff --git a/django/db/models/fields/related.py b/django/db/models/fields/related.py
index 4ff93e701f..4caed4f559 100644
--- a/django/db/models/fields/related.py
+++ b/django/db/models/fields/related.py
@@ -227,7 +227,7 @@ class SingleRelatedObjectDescriptor(six.with_metaclass(RenameRelatedObjectDescri
                 if not router.allow_relation(value, instance):
                     raise ValueError('Cannot assign "%r": the current database router prevents this relation.' % value)
 
-        related_pk = tuple([getattr(instance, field.attname) for field in self.related.field.foreign_related_fields])
+        related_pk = tuple(getattr(instance, field.attname) for field in self.related.field.foreign_related_fields)
         if None in related_pk:
             raise ValueError('Cannot assign "%r": "%s" instance isn\'t saved in the database.' %
                                 (value, instance._meta.object_name))
@@ -541,8 +541,8 @@ def create_many_related_manager(superclass, rel):
                 ('_prefetch_related_val_%s' % f.attname,
                 '%s.%s' % (qn(join_table), qn(f.column))) for f in fk.local_related_fields))
             return (qs,
-                    lambda result: tuple([getattr(result, '_prefetch_related_val_%s' % f.attname) for f in fk.local_related_fields]),
-                    lambda inst: tuple([getattr(inst, f.attname) for f in fk.foreign_related_fields]),
+                    lambda result: tuple(getattr(result, '_prefetch_related_val_%s' % f.attname) for f in fk.local_related_fields),
+                    lambda inst: tuple(getattr(inst, f.attname) for f in fk.foreign_related_fields),
                     False,
                     self.prefetch_cache_name)
 
@@ -964,11 +964,11 @@ class ForeignObject(RelatedField):
 
     @property
     def local_related_fields(self):
-        return tuple([lhs_field for lhs_field, rhs_field in self.related_fields])
+        return tuple(lhs_field for lhs_field, rhs_field in self.related_fields)
 
     @property
     def foreign_related_fields(self):
-        return tuple([rhs_field for lhs_field, rhs_field in self.related_fields])
+        return tuple(rhs_field for lhs_field, rhs_field in self.related_fields)
 
     def get_local_related_value(self, instance):
         return self.get_instance_value_for_fields(instance, self.local_related_fields)
@@ -998,7 +998,7 @@ class ForeignObject(RelatedField):
 
     def get_joining_columns(self, reverse_join=False):
         source = self.reverse_related_fields if reverse_join else self.related_fields
-        return tuple([(lhs_field.column, rhs_field.column) for lhs_field, rhs_field in source])
+        return tuple((lhs_field.column, rhs_field.column) for lhs_field, rhs_field in source)
 
     def get_reverse_joining_columns(self):
         return self.get_joining_columns(reverse_join=True)
@@ -1105,10 +1105,10 @@ class ForeignObject(RelatedField):
 
     @property
     def attnames(self):
-        return tuple([field.attname for field in self.local_related_fields])
+        return tuple(field.attname for field in self.local_related_fields)
 
     def get_defaults(self):
-        return tuple([field.get_default() for field in self.local_related_fields])
+        return tuple(field.get_default() for field in self.local_related_fields)
 
     def contribute_to_class(self, cls, name, virtual_only=False):
         super(ForeignObject, self).contribute_to_class(cls, name, virtual_only=virtual_only)
diff --git a/django/db/models/query.py b/django/db/models/query.py
index 67780a4991..5947a85730 100644
--- a/django/db/models/query.py
+++ b/django/db/models/query.py
@@ -534,7 +534,7 @@ class QuerySet(object):
         if not id_list:
             return {}
         qs = self.filter(pk__in=id_list).order_by()
-        return dict([(obj._get_pk_val(), obj) for obj in qs])
+        return dict((obj._get_pk_val(), obj) for obj in qs)
 
     def delete(self):
         """
diff --git a/django/db/models/sql/compiler.py b/django/db/models/sql/compiler.py
index 6c8b850c84..5dda379236 100644
--- a/django/db/models/sql/compiler.py
+++ b/django/db/models/sql/compiler.py
@@ -437,7 +437,7 @@ class SQLCompiler(object):
             # Firstly, avoid infinite loops.
             if not already_seen:
                 already_seen = set()
-            join_tuple = tuple([self.query.alias_map[j].table_name for j in joins])
+            join_tuple = tuple(self.query.alias_map[j].table_name for j in joins)
             if join_tuple in already_seen:
                 raise FieldError('Infinite loop caused by ordering.')
             already_seen.add(join_tuple)
@@ -866,7 +866,7 @@ class SQLInsertCompiler(SQLCompiler):
             return [(" ".join(result), tuple(params))]
         if can_bulk:
             result.append(self.connection.ops.bulk_insert_sql(fields, len(values)))
-            return [(" ".join(result), tuple([v for val in values for v in val]))]
+            return [(" ".join(result), tuple(v for val in values for v in val))]
         else:
             return [
                 (" ".join(result + ["VALUES (%s)" % ", ".join(p)]), vals)
diff --git a/django/db/models/sql/datastructures.py b/django/db/models/sql/datastructures.py
index 76b3db5b35..b32148eba5 100644
--- a/django/db/models/sql/datastructures.py
+++ b/django/db/models/sql/datastructures.py
@@ -37,7 +37,7 @@ class Date(object):
 
     def as_sql(self, qn, connection):
         if isinstance(self.col, (list, tuple)):
-            col = '%s.%s' % tuple([qn(c) for c in self.col])
+            col = '%s.%s' % tuple(qn(c) for c in self.col)
         else:
             col = self.col
         return connection.ops.date_trunc_sql(self.lookup_type, col), []
@@ -57,7 +57,7 @@ class DateTime(object):
 
     def as_sql(self, qn, connection):
         if isinstance(self.col, (list, tuple)):
-            col = '%s.%s' % tuple([qn(c) for c in self.col])
+            col = '%s.%s' % tuple(qn(c) for c in self.col)
         else:
             col = self.col
         return connection.ops.datetime_trunc_sql(self.lookup_type, col, self.tzname)
diff --git a/django/db/models/sql/query.py b/django/db/models/sql/query.py
index 1d19c5b9a8..ae67b6f20c 100644
--- a/django/db/models/sql/query.py
+++ b/django/db/models/sql/query.py
@@ -762,7 +762,7 @@ class Query(object):
         # 2. Rename the alias in the internal table/alias datastructures.
         for ident, aliases in self.join_map.items():
             del self.join_map[ident]
-            aliases = tuple([change_map.get(a, a) for a in aliases])
+            aliases = tuple(change_map.get(a, a) for a in aliases)
             ident = (change_map.get(ident[0], ident[0]),) + ident[1:]
             self.join_map[ident] = aliases
         for old_alias, new_alias in six.iteritems(change_map):
diff --git a/django/forms/models.py b/django/forms/models.py
index 4c6ee9c6ed..9df97d6960 100644
--- a/django/forms/models.py
+++ b/django/forms/models.py
@@ -543,7 +543,7 @@ class BaseModelFormSet(BaseFormSet):
 
     def _existing_object(self, pk):
         if not hasattr(self, '_object_dict'):
-            self._object_dict = dict([(o.pk, o) for o in self.get_queryset()])
+            self._object_dict = dict((o.pk, o) for o in self.get_queryset())
         return self._object_dict.get(pk)
 
     def _construct_form(self, i, **kwargs):
diff --git a/django/template/loader_tags.py b/django/template/loader_tags.py
index 224efe884b..d7908acf7f 100644
--- a/django/template/loader_tags.py
+++ b/django/template/loader_tags.py
@@ -78,7 +78,7 @@ class ExtendsNode(Node):
         self.nodelist = nodelist
         self.parent_name = parent_name
         self.template_dirs = template_dirs
-        self.blocks = dict([(n.name, n) for n in nodelist.get_nodes_by_type(BlockNode)])
+        self.blocks = dict((n.name, n) for n in nodelist.get_nodes_by_type(BlockNode))
 
     def __repr__(self):
         return '<ExtendsNode: extends %s>' % self.parent_name.token
diff --git a/django/templatetags/i18n.py b/django/templatetags/i18n.py
index 14f0382fc7..bce10b9de6 100644
--- a/django/templatetags/i18n.py
+++ b/django/templatetags/i18n.py
@@ -147,7 +147,7 @@ class BlockTranslateNode(Node):
         default_value = settings.TEMPLATE_STRING_IF_INVALID
         render_value = lambda v: render_value_in_context(
             context.get(v, default_value), context)
-        data = dict([(v, render_value(v)) for v in vars])
+        data = dict((v, render_value(v)) for v in vars)
         context.pop()
         try:
             result = result % data
diff --git a/django/utils/cache.py b/django/utils/cache.py
index 917949d4d3..45f93b9b4c 100644
--- a/django/utils/cache.py
+++ b/django/utils/cache.py
@@ -58,7 +58,7 @@ def patch_cache_control(response, **kwargs):
 
     if response.has_header('Cache-Control'):
         cc = cc_delim_re.split(response['Cache-Control'])
-        cc = dict([dictitem(el) for el in cc])
+        cc = dict(dictitem(el) for el in cc)
     else:
         cc = {}
 
diff --git a/django/utils/datastructures.py b/django/utils/datastructures.py
index a0ee3e06ef..29228bd3a5 100644
--- a/django/utils/datastructures.py
+++ b/django/utils/datastructures.py
@@ -334,7 +334,7 @@ class MultiValueDict(dict):
 
     def __getstate__(self):
         obj_dict = self.__dict__.copy()
-        obj_dict['_data'] = dict([(k, self.getlist(k)) for k in self])
+        obj_dict['_data'] = dict((k, self.getlist(k)) for k in self)
         return obj_dict
 
     def __setstate__(self, obj_dict):
diff --git a/django/utils/dictconfig.py b/django/utils/dictconfig.py
index ed1440ce11..c676035dc7 100644
--- a/django/utils/dictconfig.py
+++ b/django/utils/dictconfig.py
@@ -257,7 +257,7 @@ class BaseConfigurator(object):
             c = self.resolve(c)
         props = config.pop('.', None)
         # Check for valid identifiers
-        kwargs = dict([(k, config[k]) for k in config if valid_ident(k)])
+        kwargs = dict((k, config[k]) for k in config if valid_ident(k))
         result = c(**kwargs)
         if props:
             for name, value in props.items():
@@ -494,7 +494,7 @@ class DictConfigurator(BaseConfigurator):
                 'address' in config:
                 config['address'] = self.as_tuple(config['address'])
             factory = klass
-        kwargs = dict([(k, config[k]) for k in config if valid_ident(k)])
+        kwargs = dict((k, config[k]) for k in config if valid_ident(k))
         try:
             result = factory(**kwargs)
         except TypeError as te: